Preheat oven to 350 degrees F. Spray a 9x13-inch baking dish with non-stick spray. Set aside.
Cook penne pasta to al dente according to package directions; drain water then set aside.
In a large pot, cook and crumble ground beef until no longer pink. Drain any grease. Add onion, garlic, Italian seasoning and pizza sauce. Stir well to combine then remove from heat.
Add cooked, drained penne to the beef mixture. Stir to combine then pour mixture into the prepared baking dish, spreading out evenly. Sprinkle the shredded Mozzarella cheese all over pasta, then top cheese with pepperoni, sliced bell pepper and olives.
Cover pan with foil and bake for 25 minutes or until hot and bubbly. Carefully remove pan from oven, then carefully remove foil. Let stand 5 minutes before serving. Enjoy!